Re: [PATCH 4/4] xfs: convert drop_writes to use the errortag mechanism

[Brian Foster <bfoster@redhat.com>]

On Tue, Jun 20, 2017 at 06:11:48PM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@oracle.com>
> 
> We now have enhanced error injection that can control the frequency
> with which errors happen, so convert drop_writes to use this.
> 
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---

Nice. Looks like a simple tweak to xfs/196 too...

Reviewed-by: Brian Foster <bfoster@redhat.com>

>  fs/xfs/xfs_error.c |    3 +++
>  fs/xfs/xfs_error.h |   14 +++++++++++++-
>  fs/xfs/xfs_iomap.c |    2 +-
>  fs/xfs/xfs_mount.h |   24 ------------------------
>  fs/xfs/xfs_sysfs.c |   42 ------------------------------------------
>  5 files changed, 17 insertions(+), 68 deletions(-)
> 
> 
> diff --git a/fs/xfs/xfs_error.c b/fs/xfs/xfs_error.c
> index 81f260f..40a15e2 100644
> --- a/fs/xfs/xfs_error.c
> +++ b/fs/xfs/xfs_error.c
> @@ -55,6 +55,7 @@ static unsigned int xfs_errortag_random_default[] = {
>  	XFS_RANDOM_REFCOUNT_FINISH_ONE,
>  	XFS_RANDOM_BMAP_FINISH_ONE,
>  	XFS_RANDOM_AG_RESV_CRITICAL,
> +	XFS_RANDOM_DROP_WRITES,
>  };
>  
>  struct xfs_errortag_attr {
> @@ -157,6 +158,7 @@ XFS_ERRORTAG_ATTR_RW(refcount_continue_update,	XFS_ERRTAG_REFCOUNT_CONTINUE_UPDA
>  XFS_ERRORTAG_ATTR_RW(refcount_finish_one,	XFS_ERRTAG_REFCOUNT_FINISH_ONE);
>  XFS_ERRORTAG_ATTR_RW(bmap_finish_one,	XFS_ERRTAG_BMAP_FINISH_ONE);
>  XFS_ERRORTAG_ATTR_RW(ag_resv_critical,	XFS_ERRTAG_AG_RESV_CRITICAL);
> +XFS_ERRORTAG_ATTR_RW(drop_writes,	XFS_ERRTAG_DROP_WRITES);
>  
>  static struct attribute *xfs_errortag_attrs[] = {
>  	XFS_ERRORTAG_ATTR_LIST(noerror),
> @@ -187,6 +189,7 @@ static struct attribute *xfs_errortag_attrs[] = {
>  	XFS_ERRORTAG_ATTR_LIST(refcount_finish_one),
>  	XFS_ERRORTAG_ATTR_LIST(bmap_finish_one),
>  	XFS_ERRORTAG_ATTR_LIST(ag_resv_critical),
> +	XFS_ERRORTAG_ATTR_LIST(drop_writes),
>  	NULL,
>  };
>  
> diff --git a/fs/xfs/xfs_error.h b/fs/xfs/xfs_error.h
> index 083a6fc..cd7881f 100644
> --- a/fs/xfs/xfs_error.h
> +++ b/fs/xfs/xfs_error.h
> @@ -96,7 +96,18 @@ extern void xfs_verifier_error(struct xfs_buf *bp);
>  #define XFS_ERRTAG_REFCOUNT_FINISH_ONE			25
>  #define XFS_ERRTAG_BMAP_FINISH_ONE			26
>  #define XFS_ERRTAG_AG_RESV_CRITICAL			27
> -#define XFS_ERRTAG_MAX					28
> +
> +/*
> + * DEBUG mode instrumentation to test and/or trigger delayed allocation
> + * block killing in the event of failed writes. When enabled, all
> + * buffered writes are silenty dropped and handled as if they failed.
> + * All delalloc blocks in the range of the write (including pre-existing
> + * delalloc blocks!) are tossed as part of the write failure error
> + * handling sequence.
> + */
> +#define XFS_ERRTAG_DROP_WRITES				28
> +
> +#define XFS_ERRTAG_MAX					29
>  
>  /*
>   * Random factors for above tags, 1 means always, 2 means 1/2 time, etc.
> @@ -129,6 +140,7 @@ extern void xfs_verifier_error(struct xfs_buf *bp);
>  #define XFS_RANDOM_REFCOUNT_FINISH_ONE			1
>  #define XFS_RANDOM_BMAP_FINISH_ONE			1
>  #define XFS_RANDOM_AG_RESV_CRITICAL			4
> +#define XFS_RANDOM_DROP_WRITES				1
>  
>  #ifdef DEBUG
>  extern int xfs_errortag_init(struct xfs_mount *mp);
> diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
> index 304b79d..86f1a9f 100644
> --- a/fs/xfs/xfs_iomap.c
> +++ b/fs/xfs/xfs_iomap.c
> @@ -1097,7 +1097,7 @@ xfs_file_iomap_end_delalloc(
>  	 * Behave as if the write failed if drop writes is enabled. Set the NEW
>  	 * flag to force delalloc cleanup.
>  	 */
> -	if (xfs_mp_drop_writes(mp)) {
> +	if (XFS_TEST_ERROR(false, mp, XFS_ERRTAG_DROP_WRITES)) {
>  		iomap->flags |= IOMAP_F_NEW;
>  		written = 0;
>  	}
> diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
> index 931e9fc..e0792d0 100644
> --- a/fs/xfs/xfs_mount.h
> +++ b/fs/xfs/xfs_mount.h
> @@ -205,16 +205,6 @@ typedef struct xfs_mount {
>  	 */
>  	unsigned int		*m_errortag;
>  	struct xfs_kobj		m_errortag_kobj;
> -
> -	/*
> -	 * DEBUG mode instrumentation to test and/or trigger delayed allocation
> -	 * block killing in the event of failed writes. When enabled, all
> -	 * buffered writes are silenty dropped and handled as if they failed.
> -	 * All delalloc blocks in the range of the write (including pre-existing
> -	 * delalloc blocks!) are tossed as part of the write failure error
> -	 * handling sequence.
> -	 */
> -	bool			m_drop_writes;
>  #endif
>  } xfs_mount_t;
>  
> @@ -333,20 +323,6 @@ xfs_daddr_to_agbno(struct xfs_mount *mp, xfs_daddr_t d)
>  	return (xfs_agblock_t) do_div(ld, mp->m_sb.sb_agblocks);
>  }
>  
> -#ifdef DEBUG
> -static inline bool
> -xfs_mp_drop_writes(struct xfs_mount *mp)
> -{
> -	return mp->m_drop_writes;
> -}
> -#else
> -static inline bool
> -xfs_mp_drop_writes(struct xfs_mount *mp)
> -{
> -	return 0;
> -}
> -#endif
> -
>  /* per-AG block reservation data structures*/
>  enum xfs_ag_resv_type {
>  	XFS_AG_RESV_NONE = 0,
> diff --git a/fs/xfs/xfs_sysfs.c b/fs/xfs/xfs_sysfs.c
> index b86148a..3e52662 100644
> --- a/fs/xfs/xfs_sysfs.c
> +++ b/fs/xfs/xfs_sysfs.c
> @@ -90,49 +90,7 @@ to_mp(struct kobject *kobject)
>  	return container_of(kobj, struct xfs_mount, m_kobj);
>  }
>  
> -#ifdef DEBUG
> -
> -STATIC ssize_t
> -drop_writes_store(
> -	struct kobject		*kobject,
> -	const char		*buf,
> -	size_t			count)
> -{
> -	struct xfs_mount	*mp = to_mp(kobject);
> -	int			ret;
> -	int			val;
> -
> -	ret = kstrtoint(buf, 0, &val);
> -	if (ret)
> -		return ret;
> -
> -	if (val == 1)
> -		mp->m_drop_writes = true;
> -	else if (val == 0)
> -		mp->m_drop_writes = false;
> -	else
> -		return -EINVAL;
> -
> -	return count;
> -}
> -
> -STATIC ssize_t
> -drop_writes_show(
> -	struct kobject		*kobject,
> -	char			*buf)
> -{
> -	struct xfs_mount	*mp = to_mp(kobject);
> -
> -	return snprintf(buf, PAGE_SIZE, "%d\n", mp->m_drop_writes ? 1 : 0);
> -}
> -XFS_SYSFS_ATTR_RW(drop_writes);
> -
> -#endif /* DEBUG */
> -
>  static struct attribute *xfs_mp_attrs[] = {
> -#ifdef DEBUG
> -	ATTR_LIST(drop_writes),
> -#endif
>  	NULL,
>  };
>  
> 
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